Miniaturized magnetic valve

ABSTRACT

A miniaturized solenoid valve is provided which is suitable for integration in an electric or electronic control circuit by it being built up on a printed circuit board. The valve has a narrow elongated housing (10) with a fluidic space (26) at one longitudinal end, and a solenoid drive (12, 14) at the opposite longitudinal end. Soldering pins protrude from the base surface of the housing, which are electrically connected to the solenoid (12) of the solenoid drive. The fluidic connections are easily accessible from the top side of the housing (10).

The invention relates to a miniaturized solenoid valve comprising agenerally parallelepiped housing which contains a solenoid drive and afluidic space separated therefrom.

According to the current state of art, fluidic and electric orelectronic control circuits are built up separately. This means thatsolenoid valves of fluidic equipment are connected by means of bus linesor separate electric connecting lines to the electric or electroniccircuits. Whilst it is possible to integrate electronic components insolenoid valves, no solenoid valves for integration into electric orelectronic circuits are available.

The invention provides a miniaturized solenoid valve which is suitablefor integration in electric or electronic circuits. This is achieved inthat soldering pins, electrically connected to the solenoid drive,protrude from the base surface of the housing of the solenoid valve. Thesolenoid valve can therefore be placed directly on a printed circuitboard and soldered in.

The fluidic connections of the solenoid valve according to the inventionare preferably arranged on the top side of the housing opposite the basesurface and are therefore easily accessible for being connected withflexible hoses.

In the preferred embodiment, the housing of the solenoid valve is ofelongated construction. The width of the housing amounts, for example,to little more than 5 mm. The fluidic space is arranged at onelongitudinal end of the housing, and the solenoid drive at the oppositelongitudinal end. An actuation lamina extends from the solenoid drive tothe fluidic space. This actuation lamina is preferably swivel-mounted inthe housing, near the fluidic space by means of a jacket made of anelastic material. By virtue of this design, the actuating lamina forms alever with a large transmission ratio. The solenoid valve can thereforeoperate with low switching forces and yet switch relatively highpressures up to approximately 8 bar.

For the integration into electric and electronic circuits it isparticularly advantageous to embody the solenoid valve as apulse-controlled unit, either bistable or monostable. To this purpose,the solenoid drive preferably is provided with a permanent magnet whichcan move between two soft iron parts, and a solenoid whose current-pulseinduced magnetic field moves the permanent magnet against one or theother soft iron part, depending on the polarity of the magnetic field.Without biasing into one or the other switching position, such asolenoid valve is stable in each switching position. By the addition ofa biasing spring, the solenoid valve becomes a pulse-controlledmonostable valve.

In order to optimize the switching behavior of the solenoid valveaccording to the invention, in a further development of the invention adrive circuit is provided which for each actuation supplies a currentpulse which terminates before the respective change-over position isreached. This ensures not only an optimum switching speed but also alargely bounce-free structure, with the result that the desiredswitching positions are safely reached and maintained.

Further details and characteristics of the invention result from thefollowing description of a preferred embodiment, and from theillustration to which reference is made and in which:

FIG. 1 shows a schematic longitudinal section of the miniaturizedsolenoid valve;

FIG. 2 shows a schematic perspective view onto the base surface of thesolenoid valve;

FIG. 3 shows a schematic perspective view onto the top side of thesolenoid valve;

FIG. 4 shows a diagram to illustrate the method of operation of thesolenoid valve.

FIG. 5 shows a schematic partial longitudinal section of theminiaturized solenoid valve with the permanent magnet biased into one oftwo switching positions.

The solenoid valve has an elongated, narrow and parallelepiped housing10 consisting of two halves joined together. At one longitudinal end ofthe housing 10, there is a solenoid drive with a solenoid 12 and a core14 surrounded by it. Next to the inner end plane of the solenoid 12 andthe core 14 is a space 16 in which a permanent magnet 20 encased in anelastomer jacket 18 is arranged so that it can move between two softiron parts 22. The permanent magnet 20 is connected to one end of anelongated actuation lamina 24. The other end of the actuation lamina 24protrudes into a fluidic space 26, at the longitudinal end of thehousing 10 opposing the solenoid drive. A frame 28 of an elastomermaterial is clamped between the two halves of the housing 10 andconnected to the adjoining end of the actuating lamina 24. The actuatinglamina 24, at its end adjoining the fluidic space 26, is swivel-mountedto the housing 10 by the elastomer material of the frame 28 surroundingit. At the same time, the fluidic space 26 is sealed off from the space16 by the clamped-in elastomer frame 28. Two sealing seats 30, 32,opposing each other, are formed in the fluidic space 26, between whichthe closing element 34, moved by the actuating lamina 24 and situated onthe frame 28 made of elastomer material, can move. Three fluidicconnectors 30a, 32a and 36 are provided, leading from the fluidic space26 to the top side of the housing 10, as is schematically shown in FIG.2. From the base surface of the housing 10 protrude two soldering pins38 which are electrically connected to the solenoid 12, as isillustrated in FIG. 3.

Both the shape and the size of the housing 10, as well as thearrangement of the soldering pins 38 at its base surface are designed tosuit the standard grids of printed circuit boards. The width B of thehousing 10 is, to give an example, only 5.5 mm. The fluidic connections32a, 30a, 36 at the top side of housing 10 are easily accessible. Theymay be configured as plug connectors, hose nipples or similar.

The permanent magnet 20 in FIG. 1 is shown in an intermediate positionbetween the soft iron parts 20, 22. However, in such a position thesolenoid drive is not stable. By interaction of the permanent magnet 20with the soft iron parts 22, the permanent magnet 20 takes up one of twostable positions, that is to say it rests against either of the two softiron parts 22. These soft iron parts 22 consist of thin plates insertedinto the housing 10, e.g. by injection molding, in case the housing ismade of plastic. By the arrangement of the solenoid 12, with its axis inthe center plane of the housing 10, a magnetic field will be producedwhen current-carrying which interacts with the permanent magnet 20 and,depending on the direction of the magnetic flux, moves the permanentmagnet 20 into one or the other switching position. The direction ofmagnetic flux is, in turn, determined by the polarity of an electricpulse applied to the solenoid 12. In one embodiment of the invention,shown in FIG. 5, a biasing spring 40 is provided to spring biaspermanent magnet 20 into one of the two stable switching positions,i.e., resting against either of the two soft iron parts 22.

In order to provide the drive for the solenoid valve, a drive circuit isprovided which delivers only switching pulses of short duration in eachcase. The duration of the switching pulses is selected in such a waythat the force effect on the permanent magnet 20 ends before it hasreached its switching position. If the permanent magnet 20 has to coverthe distance OA between its switching positions, and the electricaldrive pulse starts, for example, at the point in time t₁, as illustratedin FIG. 4, then the drive pulse already ends at the point in time t₂,for example, before approximately half the distance has been covered;only at the point in time t₃ will the switching position be reached. Themovement of the permanent magnet 20 past the point in time t₂ istherefore not subjected to further acceleration, helping to preventbounce from the switching position reached when this position is reachedat the point of time t₃. The duration t₂ -t₁ of a drive pulse may, forexample, amount to 20 ms.

What is claimed is:
 1. A miniaturized solenoid valve, comprising agenerally parallelepiped housing (10) which contains a solenoid drive(12, 14) and a fluidic space (26) separated therefrom, said solenoiddrive (12, 14) including a permanent magnet (20) which can move betweentwo soft iron parts (22), and a solenoid (12) whose current-pulseinduced magnetic field moves the permanent magnet (20) against one orthe other soft iron parts (22), depending on the polarity of themagnetic field, said soft iron parts (22) being spaced from saidsolenoid (12) and supported by said housing (1O).
 2. The solenoid valveaccording to claim 1, wherein at the top side of the housing (10)opposite the base surface, fluidic connectors (30a, 32a, 36) lead out ofthe fluidic space (26).
 3. The solenoid valve according to claim 1 or 2,characterized in that the housing (10) is of elongated construction, thefluidic space (26) is arranged at one longitudinal end of the housing(10) and the solenoid drive (12, 14) at the other, and that an actuatinglamina (24) extends from the solenoid drive (12, 14) toward the fluidicspace (26).
 4. The solenoid valve according to claim 1, characterized inthat the actuating lamina (24) is swivel-mounted in the housing (10),near the fluidic space (26) by means of a jacket made of an elasticmaterial.
 5. The solenoid valve according to claim 1, wherein thesolenoid drive (12, 14) can take up two stable switching positions. 6.The solenoid valve according to claim 1, wherein the permanent magnet(20) is biased by spring force into one of two switching positions andhas a stable switching position.
 7. The solenoid valve according to anyone of the claims 1, 5 or 6, including an associated drive circuit whichfor each actuation supplies a current pulse which terminates before therespective change-over position is reached.
 8. The solenoid valveaccording to claim 5, including an associated drive circuit which foreach actuation supplies a current pulse which terminates before therespective change-over position is reached.
 9. The solenoid valveaccording to claim 6, including an associate drive circuit which foreach actuation supplies a current pulse which terminates before therespective change-over position is reached.
 10. The solenoid valveaccording to claim 1, wherein soldering pins (38), electricallyconnected to the solenoid drive (12), protrude from a base surface ofthe housing (10).